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The last 5 posts

Sunday, May 18th 2008, 9:10pm

by HooKooDooKu

I don't think there is much the city can (or will) do. From what I understand, cities are only required to supply you with something like only 35psi of water pressure. At 45-50, that's well within the likely requirements of the city.

Where did you test the static pressure? Are you sure it wasn't AFTER a pressure regulator? Most homes (where pressure regulators are needed) are setup such that they have one hose spigot before the pressure regulator and one after the regulator. The regulator will usually be preset for about 50psi (and usually require something like a minimum of something like 15psi between the incomming pressure and the regulated pressure.

But even if you only have 45psi and you have to go through an RPZ (that will steal another 12-15psi), that should be enough to still install a system. It's going to be pushing it, but possible. There are a couple of sprinklers that can operate at only 25psi. One thing frequently used when low flows are required is MPRotators. You use standard Rainbird spray bodies, but replace the nozzle with the MPRotator. I seem to recall that @25psi, the MP2000 will throw water about 17'. You might have to design several zones, but it's possible with only 5gpm.

Try to look on the bright side, if your pressure readings are right, sounds like you won't have to worry about a pressure regulator for the drip stuff.

Sunday, May 18th 2008, 6:25am

by gsamu

Thank you for all of your valuable information. Things make much more sense now. I was finally able to test my static and dynamic pressure yesterday and I was disappointed. This is what I found:

meter: 3/4"
main line 3/4"
static pressure: varies between 45 and 50
dynamic pressure: 40 psi, 1 gpm
maximum gpm: 5 psi, maximum 5 1/2 gpm

This is my existing meter for both water and sewer. I have ordered a dedicated 3/4" meter just for landscaping and it should be installed this week by the city. Between the psi and gpm, what can I ask the city to do to increase these numbers or what can I do?

Thank you

Saturday, May 17th 2008, 10:15pm

by HooKooDooKu

Using larger pipes reduce pressure losses. There is nothing wrong with using 3/4" components with a 1" water line. Usually, the smaller components will have more of a pressure loss than the larger components because of the increased restrictions. But that's about it. And even that rule doesn't always hold, especially with RPZ backflow preventers (i.e. depending upon the GPM you are designing for, it's possible to get MORE pressure loss through a 1" RPZ than you will get through a 3/4" RPZ).

Consider it this way... the sprinkler valve you are likely to use will likely have a hole that is about the diameter of a standard pencil that all the water must flow through. This will be the case whether you are using a 1" valve or a 3/4" valve. Acctually, it's even possible that the "guts" of the two sized valves will be identical. The main reason the manufacture makes the valve in 3/4" and 1" sizes is so you can get the valve to match your pipe size without having to add a reducing bushing.

I too have a combination of drip and conventional sprinklers. I'm using the Rainbird DVF (or it's equivilent) for both applications just fine. Actually, I've got one circuit that has a single drip emitter that is likely only puting out about 3gph (that's 0.05 gpm) and the valve is working just fine.

As for the RBY, that is what else where is called a Wye filter (because of its shape). When doing drip irrigation, you HAVE to have a fine mesh filter to make sure there basically isn't ANYTHING in the water because the drip emmitters will instantly clog up on the smallest of particals. And even if you are on city water, there will still be "stuff" (including fine grains of sand) that will clog the drip system. Actually, it will improve the life and reliability of your entire system to include a Wye filter between the meter and the backflow preventer. That will prevent "stuff" from getting in the backflow preventer as well as make sure fine particals don't get trapped in the valves. As an example of why you need to include a Wye filter is what I found in my system after the 1st year of use. I am on city water, and based on the annual reports we get, our water system is above average. But the first time I cleaned the filter, I found a splinter of wood about the diameter of a toothpick about 1/4" long in the filter. Something that big would easily clog any drip emmitter, and likely even a control valve. However, if you include a filter before the valves, you have to make sure it is compatible with a mainline (constant pressure). Generally, that means the filter must state that it can withstand pressures to 150psi. Here is an example of Rainbird filters: http://www.rainbird.com/drip/products/control/prfilter.htm However, I would recomend against the filter/pressure regulator combo. What you want (to minimize components) is seperate filter and pressure regulator. That way, you can use the filter before the backflow (if you used the pressure regulator there, the pressure coming out of the backflow would be something like 25psi) but then split the mainline between the "regular" valves and the "drip" valves. Then insert the pressure regulator to the mainline leading to the drip valves. (Here we go, here's the rainbird Wye filter by itself http://www.rainbird.com/drip/products/control/inline_wye.htm and the inline pressure regulators http://www.rainbird.com/drip/products/control/inline_reg.htm. The problem you can run into is that so many people just skip filtration, that it's difficult to locate them. (Well, it took a little digging, but I found then here at our sponser's web site... they were under the drip section, not the filter section http://www.sprinklerwarehouse.com/Drip-Irrigation-Filters-Screens-s/1046.htm). BTW, the larger the mesh number, the smaller the holes. For protecting the drip irrigation, you want the 200# NOT the 80#.

Friday, May 16th 2008, 3:20pm

by gsamu

This is a continuation of my first question. I am new at this as you can tell. I will be needing 8 zones, 5 will be strictly drip and 3 will be more conventional sprinkler heads. I am puzzled about which values to use considering I have two different application. Rainbird offers the Xerigation ¾” XCZ075PRF which puts out from .2 to 5.0 GPM. I will be having primarily 3-10 gallon shrubs and trees in my initial planting. Will this range of GPM be enough for small 6’-8’ trees? Rainbird also offers the XCZ100PRF - Rain Bird 1" Medium Flow Control Zone Kits with Static WYE Filter which puts out 3.0 to 15GPM. I think this is overkill but I need your opinion. I have not done a static or dynamic test yet but I don’t believe that my system will give more than 13GPM.

My last choice that may work for both drip and conventional sprinkler applications is the 1” DVF. It seems to work with pop ups as well as low flow and xerigation applications when the RBY filter is installed (what is an RBY filter).

Thank you for any help that you can give me.

Friday, May 16th 2008, 3:01pm

by gsamu

What is the correct Main Line Dimension?

I am having installed a dedicated water meter strictly for irrigation. It is a ¾” meter with a FE860-075 - Febco 3/4" Reduced Pressure Assembly. Is it possible to run the main line as a 1” line rather than a ¾” line from the RPV to the valves. I guess I am a little confused due to the water meter being ¾”. Does this mean that I need to stay with a ¾” or will increasing the main line to 1” be beneficial?